1. Field of the Invention
The present invention relates to a linear motor, a stage device, and an exposing device employed as a driving mechanism for super-precise equipment, such as semiconductor manufacturing apparatuses, measurement devices, and so forth.
2. Description of the Related Art
FIG. 9 shows the array of permanent magnets used in a known linear motor. This figure shows only one side of the permanent magnet group (stator group), wherein 70 denotes a yoke and 71 (71a through 71c) denotes permanent magnets arrayed on the yoke, each of the permanent magnets 71 being of a rectangular parallelepiped with the corners thereof having been removed. Also, the plurality of permanent magnets 71 are arrayed such that the polarity (N-pole and S-pole) thereof alternates, and the thickness and width of each of the permanent magnets are determined so as to generate a sine waveform magnetic field in the space between the stator group and an opposing stator group.
However, with the above known example, the thickness and width of each of the permanent magnets has to be changed according to the position thereof in order to generate a sine waveform magnetic field, and further, the form thereof is not a simple rectangular parallelepiped. Thus there is a problem that it is difficult and costly to manufacture the permanent magnets with high precision. Also, there is a problem that the driving force of the linear motor decreases, since the magnetic flux density is lower than that of a rectangular parallelepiped.